The present invention relates generally to communication systems, and particularly to paging systems delivering messages in common to a set of paging devices according to, for example, an information subscription service or group paging service.
Paging devices are typically small radio signal receiving and paging information storing devices carried by the paging device user as a personal accessory throughout the day. Typically, paging information, i.e., a paging message, arrives as a telephone number to be called in response to the page. The person originating the page dials a telephone number associated with a given paging device and, in response to, for example, voice prompts, enters a sequence of digits to be presented on a display of the paging device.
Paging devices have evolved, however, beyond simply delivering a telephone number to be called. Paging devices can serve as personal information terminals receiving a variety of information in addition to telephone numbers to be dialed in response to the page. Information delivered to a paging device can assume a common format, e.g., a multiple digit numeric message. While a message may appear in form as a telephone number on the paging device display, however, a prearrangement between the person originating the page and the person receiving the page can provide a basis for more sophisticated information delivery. According to such prearrangement, information delivered in the format of a telephone number, or given digit pattern, can represent anything from personal information, such as a bank account balance, to information of general interest, such as sports scores or weather information. For paging devices capable of displaying alphanumeric messages, and for message sources capable of generating an alphanumeric message, the message can be presented literally on the paging device display.
Information content delivered to a paging device used as a personal information terminal can vary according to various information service subscriptions available through the paging service. For example, a paging service can broadcast information to a number of people subscribing to a general interest information service. Such group broadcast information is delivered to subscribing sets of paging device users. For example, local weather, local sports scores, stock market information, and a great variety of other general interest information can be delivered to groups of subscribing paging device users. Information delivered can also be of personal interest and directed to a specific paging device user. For example, a bank account balance may be directed to a specific paging device user according to a service subscription with the paging service.
As may be appreciated, information of personal interest to single paging device user is handled generally in the manner of other paging messages. The message data can, for example, be submitted to the paging system by way of direct data link, as opposed to manipulation of a telephone keypad. Thus, a banking institution might deliver a batch of bank account data, including an account balance data and identification of the specific paging device to which each balance datum is to be delivered. Generally such information subscriptions are easily integrated into the paging system message delivery protocol along with other message data directed to specific paging devices. In particular, such additional personal messages do not degrade system message handling capacity.
Information subscriptions of general interest, i.e., a group message sent in common to a given set of paging devices, can impact message handling capacity of the paging system, especially a time-division multiplexed paging system protocol. The subject matter of the present invention relates to delivery of such group messages without degradation in system capacity, i.e., without stealing excessively from message delivery bandwidth.
In a conventional paging system, not a time-division multiplexed system, wherein each paging device is always active and monitoring a given radio frequency for occurrence of a specific address, group message delivery is accomplished by simply programming the paging devices to watch for additional addresses, i.e., an address for a group information subscription. When such a paging device detects a group message address of interest, i.e., one to which its user has subscribed, the paging device simply collects the associated message and displays the collected message.
In a time-division multiplexed paging protocol, however, delivering group messages can degrade system capacity. For the present discussion, a time-division multiplexed paging system associates given time intervals with one or more paging devices. The paging devices seek paging information primarily only during the associated time interval. In this manner, for example, power consumption is reduced by allowing the paging device to de-activate its radio receiving circuitry at times other than its associated time interval.
One approach to group message delivery in a time-division multiplexed paging system requires the paging system to generate individual messages, i.e., individually addressed, for each of the subscribing users of a given information service. The paging system would generate one message for each member of the group, and simply pass these messages through the system in the manner of individually addressed personal messages. Unfortunately, such a method requires additional processing overhead by the paging system in managing user profiles indicating membership in given groups, i.e., subscription to given information services, and also requires that multiple occurrences of the same message be generated and transmitted by the system.
Another approach to delivering group messages in a time-division multiplexed paging system is to flood all time intervals with the same group message. In this manner all paging devices collect the group message and, if the collected message is of interest, i.e., an information subscription service to which the user has subscribed, the paging device displays the collected message. Unfortunately, such method monopolizes the entire message delivery bandwidth for delivery of a single message to a given subset of paging devices. Also, certain messages may already be queued for transmission and the group message is delayed until an entire bandwidth of time intervals is available for flooding of the group message. While the group message is being broadcast, i.e., flooded across an entire spectrum of time intervals; regular personal message delivery is delayed. Thus, both normal or personal messages and group messages are not timely delivered.
Accordingly, it would be desirable to provide in a time-division multiplexed paging system a method for group message delivery not requiring delay in personal message delivery or in group message delivery. All messages should be timely broadcast without significant delay so as to provide prompt personal message delivery as well as up-to-date or current group message information. Furthermore, such method should not use an inordinate amount of message delivery bandwidth. Thus, broadcast of group messages should not require any significant additional message delivery bandwidth beyond that required for personal message delivery.